您可以使用String类的toUpperCase()和 toLowerCase()方法更改大小写 。
public class Sample { public static void main(String args[]){ String str = "Hello how are you"; String strUpper = str.toUpperCase(); System.out.println("Lower to upper : "+strUpper); String strLower = str.toLowerCase(); System.out.println("Upper to lower : "+strLower); } }
输出结果
Lower to upper : HELLO HOW ARE YOU Upper to lower : hello how are you